Number 7 Mansfield Street (previously number 10) is on the west side of the street, and the penultimate house at the southern end. It was built for the plasterer Joseph Rose junior (1746-99), the third generation of his family to be a master stuccoist, and who exhibited at the Royal Academy four times in 1770-98. Rose worked with the Adam brothers regularly, and was also involved in the Portland Place speculation, where he took the leases of numbers 19 and 34. Rose's own London premises were located in Queen Anne Street East.
In 1775 the lease was purchased by Henry Dillon, 11th Viscount Dillon (1705-87), nephew of the 9th Viscount, and brother of the 10th Viscount, whom he succeeded in 1741. Dillon retained the house until his death in 1787.
Number 7 is one of the surviving houses, and Adam's drawing room ceilings, and stairwell ornamentation remain in situ. The house has been the offices of the British Veterinary Association since 1954.